1. Field of The Invention
The present invention consists of a high capacity, highly efficient centrifugal liquid pump, and in its most preferred embodiment, also to a high capacity, highly efficient gas blower. Such a pump may be used to transport a wide variety of liquids to fulfill a broad range of applications.
2. Description of the Prior Art Centrifugal pumps (sometimes referred to by the pump industry as "the king of pumps") were invented in France around the middle of the nineteenth century. Before their introduction to the pumping industry, only positive displacement pumps were available (i.e., specifically, piston and rotary types). These were costly to manufacture since the machine tool industry had not been well developed and high production techniques were generally unknown. Centrifugal pumps, because of their inherent simplicity, durability and low fabrication cost, quickly replaced more expensive positive displacement pumps and the bulk of pump research and development throughout the world was slanted to the perfection of the many varieties of velocity (centrifugal) pumps required by growing industries. Today, the most widely used pump type is of the centrifugal variety since it combines many of the most desirable attributes required of pumps in general use. Small--less than 500 gallons per minute (GPM) capacity--centrifugal pumps are notoriously inefficient, due, principally, to the low velocity imparted to the fluids pumped when such pumps are driven by commonly available drive means such as 1725 RPM or 3450 RPM electric motors. In addition, small centrifugal pumps have a low ratio between contained volume and their interior surface resulting in a relatively high level of friction between the moving fluid and the impeller and pump chamber walls. Large centrifugal pumps with impellers of greater diameter and width impart high velocity to the fluids they transport and a higher ratio between contained volume and interior surface is present thereby reducing friction and improving efficiency. Comparatively few small centrifugal pumps develop hydraulic horsepower efficiencies in excess of 50 percent at maximum head in contrast to very large pumps capable of efficiencies of 91 percent and slightly higher. It is further true that the useful life of larger pumps is generally greater than that of smaller pumps since the larger pumps may be operated effectively at lower speeds, reducing wear on moving parts.
Contrary to the commonly held belief by centrifugal pump designers and engineers, it has been discovered that fluids to be pumped need not dwell in the compartments of centrifugal pump impellers for the length of time long considered essential to impart maximum velocity to the fluids pumped. The scientific principle that a moving body's kinetic energy does not change unless there is a change in its velocity may be applied to advantage in centrifugal pump design and operation. This discovery has been applied to the subject invention described below and its application combined with improved basic impeller and pump chamber design has resulted in a centrifugal pump which exhibits several desirable characteristics setting it apart from other centrifugal pumps currently known to the prior art. The present invention differs from the prior art in several respects relative to operational efficiency, energy input requirements, manufacturing costs and overall versatility owing to the following reasons.
In the past, numerous attempts have been made to improve the poor efficiency of small and medium size centrifugal pumps, these efforts devoted mainly to changes in impeller design and casing configurations. It appears the bulk of such activities have been based upon well established "scientific" rules which have caused many researchers to by pass the fundamental principles which form an integral part of the performance of such devices. It has been widely believed significant hydraulic efficiency could only be attained by physically large centrifugal pumps, that small pumps could not compete successfully because of their small size. It has been believed that pump impellers must be relatively narrow in width, that increasing the dimensions of impellers in that plane would serve no useful purpose. A further belief held that significant liquid velocity could only be obtained by causing the liquid to be pumped to travel a comparatively long path between impeller blades, to "give it time to accelerate".
The several experimental prototypes which have formed the basis for the present invention have pointed out the shortcomings of many of the earlier efforts to produce high efficiency small centrifugal pumps. It has been proven by actual tests of the experimental pumps which led to significant improvements in pump efficiency and capacity can be achieved by increasing the impeller width and reducing the impeller blade length.